Asexuality is a sexual orientation defined by a lack of sexual attraction or intrinsic desire for partnered sex. While other sexual orientations are defined around the gendered direction of attraction (e.g. heterosexual = sexually attracted to the opposite gender), asexual people simply don’t experience the “sexual” part.
Another way of wording it is as being sexually attracted to no gender. Like how heterosexuality (attraction to opposite gender) and homosexuality (attraction to same gender) are inverses of each other, asexuality (attraction to no gender) can be seen as the opposite of bi/pansexuality (attraction to multiple/all genders).

Asexual people may want to open up to others about their orientation just as anyone else would. They may want you to understand them better. They may want to express their true selves. They may want to assure you that their lack of sexuality is intrinsic to who they are and not a problem or failing.

Is this just some rebellious phase? Won't they grow out of it? It seems too young an age to determine a topic such as this.

Asexuality, like other orientations, continues on into adulthood. While some people may go through periods of uncertainty where they question their a/sexual orientation, other people may be certain of their orientation from an early age.

Do you think it's caused by sexual abuse/repressed homosexuality/another psychological issue? Should I send them to a psychiatrist?

Asexuality is a valid orientation that some people simply are. Some asexual people, like people of all orientations, may have experienced past trauma or have mental health concerns, but those are not necessarily linked to their asexuality. In fact, according to the 2015 Asexual Community Census only 5% of ace respondents said asexuality was a factor that led to them seeing a mental health professional.

No. Asexuality isn’t caused by parenting – like with other orientations, it’s just what we are. The best thing you can do as a parent/relative/friend is to provide them with a loving and accepting environment and help them build confidence in their whole selves.

Nope! Asexual individuals are just as diverse in how much love they feel towards other people, just without a sexual element. Asexuals can have different romantic orientations, meaning they may still desire romantic relationships.

I just want what's best for my child/relative/friend. What if they turn out unhappy or alone?

The healthiest thing for someone to do is to be their true selves. The best way to provide support for an asexual person is to accept their orientation and encourage them to keep pursuing what they want to pursue to make them happy. This may include finding a committed partner, or it may not. In any case, asexual people can be just as happy as people of other orientations if they’re empowered to live the life they genuinely want to live.

Should we tell the family/neighbours/teachers/etc.? What will other people think?

It’s the individual’s decision on who else knows about their asexuality. Some people are very open and vocal about it, while other people are more private. This could depend on the asexual person’s general personality, or concerns they may have about judgment from others. It’s important to let asexual individuals choose their own way of coming out, as this could have a big impact on their life.

How can my child/relative/friend have an opinion on this if they have never tried having sex?

It’s not a matter of opinion – it’s who they are. Many asexual people simply know that they’re not sexually attracted to people, or that they have no intrinsic desire to have sexual relationships with other people. This is similar to how some people just know that they’re attracted to a certain gender – they don’t need to prove that by having sex with a person of a gender they’re not attracted to.

Some people may come to the conclusion that they’re asexual after trying out sex, but that doesn’t make them any more or less asexual than people who haven’t tried it. It’s simply a matter of differences in how we learn about ourselves.

Does this mean my child/relative/friend will hate or look down upon people who have sex?

No, asexuality isn’t the same as anti-sexuality. Anti-sexuality, sometimes also called sex-negativity, is an opinion that disapproves of sexuality in society in general. Asexuality is an orientation of a person’s lack of intrinsic attraction or desire to sex with other people. While people can be both asexual and anti-sexual/sex-negative, it’s also possible for people to be both asexual and sex-positive if they support healthy sexuality in broader society. Asexual people can still be taught the values of acceptance of sexuality, even if they don’t want to have sex themselves.

Sex is a natural part of existence. What is my child/relative/friend ashamed or afraid of?

It’s not about being ashamed or afraid of sex – it’s simply about intrinsically not being sexual. In general, sex is a natural part of existence for most people. Asexuals are just the exception to that. Many people will start off being ashamed or afraid of sex. For sexual people, it’s usually just a matter of getting over those awkward first experiences before they’re familiar and comfortable with sex and their sexuality that drives them. Asexual people don’t have a sexuality drive them. Even overcoming awkward first experiences won’t change that. It’s simply who they are.

Be supportive. Listen to them. Acknowledge that asexuality is a valid orientation. Tell them it’s okay to be who they are. Give them the time and space they need to come to terms with their own identity. Don’t pressure them to try out things they don’t want to do. Respect their privacy. Advocate for awareness of asexuality in general, to help make the world more accepting of them. There are many things that family, friends, educators, and communities can do for asexuals or people under the ace umbrella, but the most constructive of them are simply listening and accepting them for who they are.